Relating one's social support network to one's mid term grade

Much has been written about the relation of social support to health outcomes. Support networks were found to be predictive of health status. Not so clear was the manner in which social support helped the individual to avoid health complications. Whereas some aspects of the support network were protective, others were burdensome. Duties to one's network could serve as a stressor and duties outside one's network might stress the support system itself. Exposure to one's network was associated with certain health risks while disruption in one's social support network was associated with other health risks.^ Many factors contributed to the impact of a social support network upon the individual member: the characteristics of the individual, the individual's role or position within the network, qualities of the network and duties or indebtedness of the individual to the network. This investigation considered the possibility that performance could serve as a stressor in a fashion similar to an exposure to a health hazard.^ Because the literature includes many examples of studies in which the subjects were college students, academic progress is a performance common to most subjects. A profile of the support networks of successful students was contrasted with those of less successful students in this correlational study.^ What was uncovered in this investigation was a very complex web of interrelated constructs. Most aspects of the social support network did not significantly predict academic performance. Only a limited number of characteristics were associated with academic success: the frequency of support, student age, the existence of a 'mentor' within one' s network, and the extent to which one received a predominant source of support. Other factors had a tendency to be negatively correlated with midterm grade, suggesting those factors may impede academic performance.^ Medical status did not predict grades, but was correlated with many aspects of the network. Disruptions in particular parts of one's network were correlated with particular health categories. In fact, disruption in social support was more predictive of academic outcomes than medical complications. Whereas the individual's values were related to the contributing factors, only the individual's satisfaction with certain aspects of the support network were predictive of higher midterm grades in a psychology class. Dissatisfaction was associated with lower grades, suggesting a disruptive effect within the network. Associations among the features of support networks which predicted academic progress were considered. ^

Functional studies of a LIM -homeodomain transcription factor lmx1b in murine mid -hindbrain and limb development

This thesis is centered on applying molecular genetics to study pattern formation during animal development. More specifically, this thesis describes the functional studies of a LIM-homeodomain gene called lmx1b during murine embryogenesis. Lmx1b expression is restricted to the mid-hindbrain junction as well as to the dorsal mesenchyme of the limb, suggesting important functions during mid-hindbrain and limb development. To test these possibilities, lmx1b homozygous mutant mice were generated and their limb and CNS phenotypes examined. Lmx1b homozygous mutant mice exhibit a large reduction of mid-hindbrain structures, and that their limbs are symmetrical along the dorsal-ventral axis as the result of a dorsal to ventral transformation. Taken together, these studies define essential functions for lmx1b in mid-hindbrain patteming and in dorsal limb cell fate determination. However, the molecular mechanisms which accounts for these phenotypes are unknown, and whether lmx1b has same or distinctive functions during the mid-hindbrain and limb development is also unclear. ^ Recently, insight into molecular mechanisms of mid-hindbrain patterning and limb development has resulted from the identification of several factors with restricted expression patterns within these regions. These include the secreted factors wnt-1, fgf-8, wnt-7a and the transcription factors pax-2, and en-1. Targeted disruption of any of these genes in mice suggests that these genes might be involved in similar regulatory pathways. Analysis of the expression of these genes in lmx1b mutants demonstrates that lmxlb is not required for the initiation, but is required to maintain their expression at the mid-hindbrain junction. Thus, lmxlb is not required for specifying mid-hindbrain cell fates, rather, it functions to ensure the establishment or maintenance of a proper organizing center at the mid-hindbrain junction. Interestingly, lmxlb functions cell non-autonomously in chimera analysis, which indicates that lmx1b might regulate the expression of secreted factors such as wnt-1 and/or fgf-8 in the organizing center. In contrast, lmx1b functions cell autonomously in the dorsal limb to govern dorsal ventral limb development and its expression is regulated by with wnt-7a and en-1. However, single and double mutant analysis suggest that all three genes have partially overlapping functions as well as independent functions. The results point toward a complicated network of cross-talks among all three limb axes. ^